Caption: Light micrograph of a section through a young thymus gland showing the detail of a thymic lobule with an outer cortex (pink) and inner medulla (at centre). The cortex largely contains developing T-lymphocytes, a type of immune white blood cell. The thymus is a gland in the lower part of the neck that is involved in the maturation of lymphocytes and thus it is an important part of the immune system. Magnification: x100 at 24x36mm size.